Two unauthorised flags were flown on the roof of Stormont for a period yesterday - prompting anger from unionist politicians who have demanded answers over how the incident happened.

However, it emerged today during a briefing of the Assembly Commission that the official internal investigation has been halted while police look into the matter.

The DUP’s Paula Bradley said authorities cannot hide behind a police investigation into the security breach.

She said she will write to the Health & Safety Executive to try and establish whether proper safety logs were being kept for those who had access to the roof.

Contractors are currently working in the building renovating parts of the roof and fourth floor.

DUP MLA Paula Bradley (Image: mydup.com)

Ms Bradley said: “The Commission meeting today was entirely unsatisfactory in terms of establishing what action will be taken to investigate this incident.

“If an individual was able to access the roof of any Parliament or legislature across the world and erect an unauthorised flag on the building there would undoubtedly be an investigation by both the police and the managing authorities of the building.

“This should be no different in Northern Ireland.

“It is for the police to decide whether a criminal offence occurred and how they might pursue that.

“The Assembly, however, needs to establish the detail of how this security breach occurred.

“There is absolutely nothing to prevent that being taken forward but Commission members were told we would be given no information either today or at the next meeting on Monday about the logs for those who entered the building and the construction area or whether all procedures were properly administered.”

Ms Bradley said she has questioned whether proper security procedures have been in place in recent weeks.

“There are issues for both the Northern Ireland Assembly and the contractor if the proper procedures have not been in place to log those entering an active construction site on the roof of Parliament Buildings,” she continued.

“As well as now pursuing this with the Health and Safety Executive I will continue to press the Assembly authorities through the Commission to finally recognise the issues at stake and properly investigate them.’

Notorious loyalist killer Michael Stone launched a murder bid on Sinn Fein’s Martin McGuinness and Gerry Adams during the infamous attack on November 24 in which he raided the building armed with explosives and other weapons.

Television film crews at Parliament Buildings to cover developments in the political process captured the moment he burst through the main door and was wrestled to the ground by two security guards.

Stone later claimed the failed murder attempt was performance art but he was later convicted and jailed for 16 years.

Stone gained notoriety in 1988 when he killed three mourners at an IRA funeral in west Belfast.

There was a major review of security at Stormont after the 2006 attack by Stone, which resulted in access to the building being restricted.